Recent developments in avian transgenesis have allowed the modification of avian genomes for exogenous protein production. Germ-line transgenic chickens can be produced by injecting replication-defective retrovirus into the subgerminal cavity of chick blastoderms in freshly laid eggs. See, for example, U.S. Pat. No. 7,511,120, issued Mar. 31, 2009, the disclosure of which is incorporated in its entirety herein by reference; issued U.S. Pat. No. 7,338,654, issued Mar. 4, 2008, the disclosure of which is incorporated in its entirety herein by reference; and US patent publication No. 2008/0064862 published Mar. 13, 2008, the disclosure of which is incorporated in its entirety herein by reference.
By weight, approximately 60% of an avian egg is composed of albumen which is composed of four major protein components; ovalbumin, ovomucoid, lysozyme and ovotransferrin with ovalbumin and ovomucoid being present in the greatest quantities. Use of regulatory sequences of genes which encode these proteins allows for expression of a heterologous gene product in the oviduct of a transgenic avian which is typically significantly advantageous over ubiquitous expression in the bird. That is, the consequences of ubiquitous expression of a bioactive gene product throughout the host animal is often undesirable. For example, in certain instances the ubiquitous presence of recombinant protein may be harmful to the development of the avian leading to death of the bird. Alternatively, the bird's health may be negatively effected leading to reduced levels of protein production.
Many currently accepted methods of producing therapeutic cytotoxic antibodies result in a less than optimum antibody dependent cellular cytotoxicity (ADCC) level of the antibody. What is needed are improved therapeutic antibodies including novel and improved forms of cytotoxic antibodies such as anti-CD20 antibodies.